A group of 5 people are going to meet weekly at the library for 4 weeks. Each week, two people are selected at random to speak. Each person may speak in multiple weeks, but no pair of people will speak together more than once. What is the probability that there is a person who will never be asked to speak?

April 4th 2013, 12:03 PM

Plato

Re: Probability Question

Quote:

Originally Posted by Mrdavid445

A group of 5 people are going to meet weekly at the library for 4 weeks. Each week, two people are selected at random to speak. Each person may speak in multiple weeks, but no pair of people will speak together more than once. What is the probability that there is a person who will never be asked to speak?

Have you done any work on this question?

How many possible pairs are there?
How many ways can we select four of those pairs?
How many of the pairs do not contain person A ?
How many ways is person A not chosen?
What is the probability that person A not chosen?